The long-term objective of this grant is to study the microbial composition of developing dental plaque. A predominant cultural study will compare the microbiota of sites with no attachment loss and sites with the earliest detectable lesions. Suspected periodontal pathogens will be sought in deeper pockets of the same oral cavity to determine whether early lesions are an extension of an existing infection or represent a new (different) infection. Screening for, and directing treatment against, species related to initial changes could prevent periodontal destruction. A second study will seek to determine if local periodontal therapy can change the microbiota and eliminate suspected periodontal pathogens from early lesions. Plaque development, with continued presence of pathogens and persisting disease will suggest that alternate, more effective treatments will be necessary. The third specific aim concentrates on the development of methods to identify microorganisms in plaque samples. Definition of the microbiota of a site requires knowledge of the species present and sensitive methods to identify them. This specific aim will investigate methods to optimize use of polyacrylamide gel electrophoresis (SDS-PAGE) of total cell proteins so that pure cultures from periodontal pockets can be identified accurately and rapidly. If unidentifiable species are found, a combination of biochemical features, SDS-PAGE and DNA/DNA hybridizations will be used to define the taxonomic groups of gram negative and positive rods. This will greatly help investigators describe the microbiota related to periodontal health and disease.